Papillary thyroid carcinoma and its variants in tertiary care hospital at rural area

Papillary thyroid carcinomas constitute more than 70% of thyroid malignancies. While the most common variants are conventional and follicular, uncommon variants such as oncocytic, diffuse sclerosing etc are also observed. The most common etiological factor is radiation, but genetic susceptibility and other factors can also contribute to the development of papillary thyroid carcinoma (PTC). Aims and Objectives: The aim of our study was to analyze different variants of papillary thyroid carcinoma at the Kamineni Institute of Medical Sciences, Narketpally. In the Nalgonda district, thyroid carcinoma constituted 1% and 2% of all incident cancers among males and females, respectively. Materials and Methods: Our data base included a total of 356 patients (non neoplastic 219 and neoplastic 137). Consecutive cases of papillary thyroid carcinoma admitted to the Kamineni institute of medical sciences were 52 (9 males and 43 females) over a period of four years. Results: The diagnosis of thyroid cancer was confirmed by fine needle aspiration cytology in most (88%) of the cases. There was a female preponderance (9 males and 43 females). The primary modality of treatment was surgery with total thyroidectomy being performed in 82%, while the rest underwent hemithyroidectomy. The papillary carcinomas were subcategorized based on the pattern. Most of the cases were conventional type [61.52%] followed by follicular variant PTC [21.2%], encapsulated [9.6%] and one each case of oncocytic type, Sclerosing variant, tall cell variant, PTC with anaplastic changes [1.92%] each. Conclusion: The purpose of this study was to review and compare the various histopathological patterns of PTC with those of classical PTC. Different variants or histological patterns may co-exist in the same tumor. High dietary intake of iodine was the most significant risk factor for the etiology of papillary thyroid carcinoma in our study. © 2019 Published by Innovative Publication. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by/4.0/)


Introduction
For the past few decades there has been an increasing incidence of PTC worldwide. Papillary thyroid carcinoma (PTC) is the most common type of malignant thyroid tumor constituting more than 70% of thyroid malignancies. 1,2 PTC constitutes 50% -90% of differentiated follicular derived thyroid cancers world-wide. It is generally seen * Corresponding author. E-mail address: dr saritha14@yahoo.co.in (S. Karre).
in areas having iodine-sufficient or iodine-excess diets.
Dietary iodine concentration has been found to influence the incidence and morphology of this disease. Thus there are significant geographic variations, but this wide variability may also be attributed to variations in sampling techniques.
According to GLOBOCAN -2008 the estimated age standardized annual incidence for thyroid carcinoma is 1 to 2.9 cases per 100,000 men and 3.4 to 9.1 cases per 100,000 women with lower figures being from developing countries and higher figures from developed countries. However the genetic predisposition to such mutations should also be considered. Hashimoto's thyroiditis increases the risk of papillary carcinoma. Some syndromes are also predisposed to the development of papillary carcinoma.
According to a long term follow up study from the Mayo clinic, the cancer related mortality is only 6.5%. 3 A study was conducted to correlate the fine needle aspiration and histopathologic findings and to study the histopathologic variants of papillary carcinoma. Many morphological variants of papillary thyroid carcinoma have been described and their be haviors have been characterized. 4

Materials and Methods
The present study was conducted at Kamineni Institute of Medical Sciences, Narketpally for a period of three year from July 2013 to June 2016. Detailed medical history was obtained and complete physical examination was performed on all patients before surgery. All patients underwent complete radiological examination comprising chest radiography, cervical ultrasonography and fine needle aspiration of thyroid nodules or cervical adenopathy at the time of admission. Depending on the cytological results and extent of the lesions, surgeries were performed. Age and sex incidence of disease presentation, distribution of cases and various clinicopathologic presentations have been analyzed.

Results
In a four year prospective study from Jan 2013 to Dec 2016 we received 356 thyroid specimens, which included both non-neoplastic and neoplastic lesions ( Table 1). The neoplastic lesions were further classified as benign and malignant lesions ( Table 2).
The malignant lesions predominantly include papillary carcinomas (81.25%) followed by follicular (14.06%) and medullary carcinomas (4.69%) ( Table 3). In this study our discussion mainly focuses on variants of papillary carcinoma encountered in our institution.
FNAC was done in all the cases. Proper history was obtained and thorough examination was performed and data with respect to size, consistency, lymphadenopathy and other related symptoms were recorded at the time of the procedure. The cases were reported after thorough screening of slides with correlation to clinical details. The post operative specimens were collected and routine histopathologic processing was done. Multiple sections were given from all specimens. The cytological and histopathologic diagnoses were compared.

Discussion
In our four year study from Jan 2013 to Dec 2016 we received 356 thyroid specimens which included both nonneoplastic and neoplastic lesions ( Table 1). The neoplastic lesions were further classified as benign and malignant (  Table 3). In our study we are discussing on the variants of papillary carcinoma encounte red in our institute over a three year duration.
The conventional PTC was seen in 32 cases [61.52%]. The microscopy showed complex papillary structure with thin fibrovascular cores (Figure 2A). The papillae are lined by cuboidal cells. The nuclear features were seen in all cases, 2 cases showed lymph node metastasis, 3 cases of classical PTC were associated with Hashimoto's thyroiditis ( Figure 4A&B). Five [9.6%] cases showed marked cystic change on both macroscopic and microscopic observation. Goitre was co-existent with 2 cases [3.8%], 14 cases out of 32 showed psammoma bodies [43.85%]. All multifocal PTC were of conventional type.
The follicular variant papillary carcinomas were predominantly characterized by follicular architecture (Figure 3A) with nuclear features ( Figure 3B) of papillary carcinoma (one case of follicular variant papillary thyroid carcinoma was associated with Hashimoto's thyroiditis). Two cases out of eleven [18.21%] showed Psammoma bodies and nuclear groove was seen in 3 cases. Five cases out of eleven were diagnosed as FVPTC on FNAC and confirmed on histopathology. Lymph node metastasis ( Figure 5A&B) was seen in 3 cases of FVPTC. The prognosis of the tumors is similar to the typical PTC. An exception is the diffuse or multinodular follicular variant which has aggressive behavior. 9 In encapsulated variant the PTC was well encapsulated by thin capsule. The cells were arranged in small papillary structures the nuclear features were seen in all cases. Two cases showed nuclear groove. None of these variants showed lymph node metastasis or psammoma bodies. This variant constitutes 4 to 14% of all papillary carcinoma, the patients tends to be younger with lower rate of lymph node metastasis (12-38%). The prognosis is excellent with all patients remaining disease free after treatment.
The oncocytic variant (1 case) showed sheets of larger cohesive cells with abundant eosinophilic and granular cytoplasm( Figure 3D). The nuclear clearing (Orphan Annie eye nuclei) was seen in >60% of tumor cells. No psammoma bodies were seen. This was focal stromal fibrosis.
One case of Tall cell variant was seen with classical papillary architecture but lined by tall cells with abundant eosinophilic cytoplasm and nuclear features that of PTC. This was first described in 1976 by Hawk and Hazard as an aggressive variant of PTC, it represents 3.8%-10.4% of PTC. To consider TCVPC there must be 30-50% tall cells in the tumor. 10 One case of diffuse sclerosing variant ( Figure 4C)of PTC on histology showed dense fibrous areas with areas of conventional PTC, there were collections of lymphocytic aggregates in background. Multiple psammoma bodies were seen.
One case of Conventional PTC showed foci of poorly differentiated tumor cells. The cells were large pleomorphic with irregular hyperchromatic nuclei and abundant eosinophilic cytoplasm. This was given as PTC with anaplastic differentiation. In a study by Albores Sarivedra et al., consisting of 109 anaplastic carcinomas, 46.8% of cases were coexistent with PTC. 11 In a similar study conducted by Muhammad Muzaffar et al., on 82 cases of PTC, conventional PTC was most common 70.7% followed by follicular variant (13), columnar cell type (6), tall cell variant (3) and each case of encapsulated and occult. Lymph node metastasis was seen in 15.5% and psammoma bodies were seen in 34% cases. 12

Conclusion
In our study we conclude that the papillary carcinoma of thyroid was most common malignancy of the thyroid gland with female predominance. The youngest patient was 9 year female and oldest patient was 67 yrs male. On FNAC papillary carcinoma diagnosis had a sensitivity of 79%. On histopathology conventional type of PT.

Source of funding
None.

Conflict of interest
None.